The present invention relates to a computerized system for scheduling work orders for manufacturing products in a manufacturing process.
Prior to the introduction of computerized scheduling systems, the scheduling of work orders in a manufacturing facility was performed manually. The person responsible for determining the work schedule manually assigned the work to be performed to specific dates. The manual scheduling process involved determining what work has to be performed and the time, materials, and resources (i.e., machines, workers, tools, etc.) required to perform it, as well as other information which influenced the schedule, such as which work was more important than other work. This process is costly, very tedious and often inaccurate. The frequency with which the scheduling process must be performed contributes to the difficulty of obtaining timely, accurate manual scheduling.
As commercial computer systems became available, manufacturers began using computerized systems that assisted in the storage and retrieval of information relevant to the scheduling of work in a manufacturing facility. In the late 1950""s and during the 1960""s, efforts were made to implement Material Requirements Planning or MRP. MRP was limited in scope to dealing only with material requirements (i.e., which parts or materials were needed and when). These early computerized systems were not capable of scheduling operations based upon the availability of materials or resource capacity.
During the 1970""s and 1980""s, many commercially available systems were created which provided more comprehensive MRP, and it was eventually renamed Manufacturing Resource Planning. The new MRP dealt with additional problems, such as forecasting, inventory management, shop floor control, engineering, and change management. Some of these systems dealt with the capacity of the plant to perform the work. One such approach was called rough-cut capacity planning and, as the name suggests, it provided a crude estimate of the capacity needed to satisfy work requirements. Rough-cut capacity planning determined the capacity needed, but was not capable of scheduling work orders based on capacity limits.
Other systems for scheduling work orders in a manufacturing facility relied on a method of scheduling that compared the total hours of capacity to the total hours of load from operations. Such systems were not capable of xe2x80x9cevent-orientedxe2x80x9d scheduling, i.e., assigning a particular event or operation to a particular resource for a particular time period.
It was not until the mid-1980""s that a computerized event-oriented scheduling system was developed that was capable of scheduling work orders and the operations required to carry out the work orders, taking into account the finite capacity of the various resources needed for the manufacturing process, i.e., finite scheduling. ProfitKey, a New Hampshire-based company, developed one of the first such finite scheduling systems available to the market. Using the ProfitKey scheduler, a manufacturer could determine the start and finish date of work orders and their operations based upon resource capacity and availability. A similar system was developed by Lilly Software Associates, Inc. and marketed as part of the VISUAL Manufacturing(trademark) system beginning in early 1993.
However, neither the ProfitKey system nor the early 1993 version of the VISUAL Manufacturing(trademark) system was capable taking the availability of materials into account in determining the scheduling of work orders. In addition, the ProfitKey system and the early 1993 version of the VISUAL Manufacturing(trademark) were both limited to a single resource capacity calendar for all resources in the system, and neither system was capable of generating multiple schedules based on different assumptions regarding resource capacity for individual resources. Further, the ProfitKey system was not capable of scheduling multiple dissimilar resources concurrently based upon user specifications.
Other scheduling systems include Microsoft Project(trademark) and Norton""s Timeline from Symantec. These programs are capable of storing and retrieving information about a project defined by the user using a method consistent with Critical Path Method (CPM) theory. These tools are designed to handle projects that have definable events that are interdependent, similar to a single work order in a manufacturing process. These systems are not, however, capable of managing hundreds of work orders at a time as is typical in most manufacturing plants.
No prior art system, is capable of scheduling a plurality of work orders or operations in a manufacturing facility, using a finite, event-oriented scheduling process with the added feature of taking into account the availability of materials that are used in the manufacturing process.
Therefore, it is an object of the present invention to provide a computerized system for performing accurate and timely scheduling of work orders in a manufacturing facility.
It is a further object of the invention to provide a method and means for scheduling work orders for manufacturing products in a manufacturing process, wherein each operation in the work order is assigned resource capacity, a start date/time, and a finish date/time based upon the resource and material requirements of the operation and the availability of resource capacity and materials in the manufacturing facility.
It is still a further object of the invention to provide a method and means for determining the best fit of the operations of each work order in the schedule based upon both resource availability and material availability.
It is still a further object of the invention to provide a scheduling system which includes a method and means for defining variable resource capacity as a function of the dates and times in the calendar individually for each resource used in the manufacturing facility.
It is still a further object of the invention to provide a scheduling system which includes a method and means for creating multiple schedules based on different resource capacity calendars for comparison purposes.
It is still a further object of the invention to provide a scheduling system which includes a method and means for scheduling operations at more than one dissimilar resource simultaneously.
It is still a further object of the invention to provide a scheduling system which includes a method and means for allowing the user to specify a minimum and maximum resource capacity needed to perform each operation being scheduled, in order to optimize utilization of each resource in the manufacturing facility.
These and other objects and advantages of the invention will be apparent from the following detailed description of the invention and drawings.
In accordance with the present invention, a computerized system is provided for scheduling a plurality of work orders in a manufacturing process. Each work order to be scheduled specifies a set of operations to be performed using a plurality of resources and materials. The method of the invention includes receiving data in a computer, the data including resource availability information for each resource used in the manufacturing process, material availability information for each material used in the manufacturing process, and work order information. The work order information includes a release date for the work order, a want date for the work order, operations information, and material requirements information. The operations information includes the identity and sequence of operations to be performed for the work order, the identity of the resources needed to perform each operation, a minimum resource capacity needed to perform each operation, and the time needed to perform each operation. The materials information includes the identity of the materials needed to perform each operation and the quantity of each material needed for the operation. The method of the invention further includes the steps of assigning resource capacity and a start date/time and a finish date/time to each operation based upon the resource availability information, the material availability information, and the work order information. The method of the invention also includes the step of displaying on a computer screen the assigned resource capacity, the assigned start date/time, and the assigned finish date/time for each operation in a graphical format.
The system of the invention includes means for receiving data in a computer, the data including resource availability information for each resource used in the manufacturing process, material availability information for each material used in the manufacturing process, and work order information. The work order information includes a release date for the work order, a want date for the work order, operations information, and material requirements information. The system of the invention further includes means for assigning resource capacity and a start date/time and a finish date/time to each operation based upon the resource availability information, the material availability information, and the work order information. The system of the invention also includes means for displaying on a computer screen the assigned resource capacity, the assigned start date/time, and the assigned finish date/time for each operation. A graphical format.
A xe2x80x9cwork orderxe2x80x9d order is a request to manufacture one or more distinct parts in a manufacturing facility. Such parts may be consumed either by the customer who ordered the parts or by other work orders within the manufacturing facility, as in the case of a subassembly.
A xe2x80x9cpartxe2x80x9d is any distinct unit that can be manufactured as an end product or an intermediate product or subassembly.
An xe2x80x9coperationxe2x80x9d is a step in the process for manufacturing a distinct part according to a work order. Each operation in a work order is sequenced so that it follows a preceding operation (or is the first), and comes before a succeeding operation (or is the last).
A xe2x80x9cmaterialxe2x80x9d is any material or part that is consumed by the manufacturing process or added to the part being manufactured during the manufacturing process. A material may be a subassembly which is an intermediate product used in the manufacturing process. A material may be identified by an inventory part number.
A xe2x80x9cresourcexe2x80x9d is something that is needed to perform an operation, but which is not directly consumed in the performance of the operation. Examples of a resource include workers, machines, and tools. A resource may be internal or external to the manufacturing facility. An external resource would be, for example, an outside vendor or an outside service provider.
A xe2x80x9cdate/timexe2x80x9d is a specification of a date (month, day, and year) and a time of day.